Freezer

Thousands of years ago, ancient Mesopotamians discovered that cold food rotted more slowly than food left outside. So, they dug big pits into the ground, insulated them with straw or sand, and then topped them with ice and snow from the nearest mountains. These pits, or ice caves, were used to preserve the food for two or three weeks at a time. Mesopotamians understood that warm air from outside could prevent the snow from cooling the food, so the entrance was kept small and narrow to prevent air seepage.

This was how food was preserved for centuries until about the late 1600s when England and France created their own version with the invention of the ice house. Although many were at least partially in the ground, some were designed as thatched roof pits that could keep food cold or provide chipped ice for drinks and desserts — with the help of snow and ice brought in from lakes — for about a year. The process was similar to the ice cave, with an insulator such as sawdust or small branches that was topped with snow and sawdust.

These eventually gave way to the creation of the icebox, a small cabinet that had a compartment for holding a large block of ice and another compartment for storing food. These were common until about the 1920s, when electric refrigerators and freezers began to make their debut.

By then, science and industry had established the idea of mechanical refrigeration, in which a circulating chemical gas kept things in a compartment cold.

Types of Freezers

The only difference between a refrigerator and a freezer is temperature. The refrigerant moves through the freezer at a faster pace to maintain that core temperature of 0 degrees Fahrenehit (-18 degrees Celsius). For a fridge, the vapor travels a bit slower, because a fridge needs to be set only at about 32 degrees Fahrenheit (0 degrees Celsius).

In your home, you probably have a refrigerator/freezer combination unit. Whether you have a side-by-side fridge/freezer appliance, the kind with the freezer on top, or one with the freezer on the bottom, the differences are few. Each freezer is a single unit, so they all use the same machinery in the pursuit of vapor compression. About the only difference is energy efficiency. The bottom-mount uses the least amount of power Why? If the compressor is on the bottom, doesn’t have to push vapor very far. On the side-by-side or top-freezer styles, the compressor has to force refrigerant through a tube to reach the freezer compartment.

Another kind of freezer is the standalone, also called a “deep freeze” or “sub-zero,” although the latter is a trademarked name for a specific brand of freezer. They, too, operate on the basic principles of vapor-compression.

The Frosty Menace: Freezer Frost

The worst thing that can happen to a freezer is frost, which is a thick, cold dusting of fine ice that covers everything inside the freezer turning it all into one big solid icy mess. What can cause frost? Opening it too often and allowing too much warm room temperature air in, which can shut down the freezer elements that are built to process only cold air. Blocking air flow by pushing the freezer too close to a wall, which makes the condenser coils act less efficiently. Having a loose rubber seal around the door, which allows that pesky room temperature air in.

Basically, in each of these situations, warm air mixes with sub-freezing air. The result is frost. Many newer-model freezers have an automatic frost prevention feature, which regulates temperatures to keep the inside temperature consistently where it needs to be. If you don’t have that feature, here are some other ways to prevent frost:

Set your freezer’s thermostat to 0 degrees Fahrenheit — not too much colder or warmer. Open it only when you need to, so as to not wear down the rubber seal around the door. If your freezer has coils on the back, make sure you have at least 3 inches between the coils and the wall.

If you aren’t able to get rid of frost as fast as it accumulates — say your rubber seal is shot, an expensive internal part is overworked, or a coil is fried — it might be time to get a replacement.